The relationship between the emergence of Batrachochytrium dendrobatidis, the international trade in amphibians and introduced amphibian species

Chytridiomycosis is an emerging infectious disease of amphibians caused by the chytrid Batrachochytrium dendrobatidis. The disease has been associated with global amphibian declines and species extinctions, however the principle drivers that underly the emergence of chytridiomycosis remain unclear. Current evidence suggests that the world trade in amphibians is implicated in the emergence of chytridiomycosis. Here, we review the evidence that the amphibian trade is driving the emergence of chytridiomycosis by (1) spreading infected animals worldwide, (2) introducing non-native infected animals into naïve populations and (3) amplifying infection of amphibians by co-housing, followed by untreated discharge of infectious zoospores into water supplies. We conclude that the evidence that the amphibian trade is contributing to the spread of Batrachochytrium dendrobatidis is strong, and that specific actions are necessary to prevent the introduction of the pathogen into thus-far uninfected areas. Specifically, we recommend the development of national risk-abatement plans, focused on firstly preventing introduction of Bd into disease free areas, and secondly, decreasing the impact of the disease on populations that are currently infected.